Buggy code:
public class WelcomeScreen extends JFrame { private static final long serialVersionUID = 1L ; private JLabel mainblock ; private JButton startButton ; public WelcomeScreen ( String UITitle ) { } private void initialiseUI ( final Container display ) { final JPanel mainPanel = new JPanel ( ) ; <START_BUG> mainblock = new JLabel ( "<html><div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-family:<seq2seq4repair_space>Avenir;<seq2seq4repair_space>font-weight:<seq2seq4repair_space>bold;<seq2seq4repair_space>font-size:<seq2seq4repair_space>52pt;\">Team<seq2seq4repair_space>G<//div><div<seq2seq4repair_space>div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-size:<seq2seq4repair_space>18pt;<seq2seq4repair_space>font-family:<seq2seq4repair_space>Avenir;\"><br>This<seq2seq4repair_space>software<seq2seq4repair_space>application<seq2seq4repair_space>is<seq2seq4repair_space>developed<seq2seq4repair_space>under<br><seq2seq4repair_space>the<seq2seq4repair_space>supervision<seq2seq4repair_space>of<seq2seq4repair_space>Professor<seq2seq4repair_space>Chris<seq2seq4repair_space>Johnson.<br>The<seq2seq4repair_space>program<seq2seq4repair_space>is<seq2seq4repair_space>based<seq2seq4repair_space>on<seq2seq4repair_space>the<seq2seq4repair_space>works<seq2seq4repair_space>of<seq2seq4repair_space>Arnaud<seq2seq4repair_space>Prouzeau.<br><seq2seq4repair_space><br><div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-size:<seq2seq4repair_space>12pt;\">Please<seq2seq4repair_space>be<seq2seq4repair_space>aware<seq2seq4repair_space>that<seq2seq4repair_space>not<seq2seq4repair_space>all<seq2seq4repair_space>satellite<seq2seq4repair_space>images<seq2seq4repair_space>are<seq2seq4repair_space>available<seq2seq4repair_space>for<seq2seq4repair_space>every<seq2seq4repair_space>location.<br>The<seq2seq4repair_space>trajectory<seq2seq4repair_space>is<seq2seq4repair_space>not<seq2seq4repair_space>based<seq2seq4repair_space>on<seq2seq4repair_space>complex<seq2seq4repair_space>formulae.<br>For<seq2seq4repair_space>help,<seq2seq4repair_space>hover<seq2seq4repair_space>over<seq2seq4repair_space>each<seq2seq4repair_space>component<seq2seq4repair_space>to<seq2seq4repair_space>view<seq2seq4repair_space>a<seq2seq4repair_space>tooltip." ) ; <END_BUG> startButton = new JButton ( "Start" ) ; startButton . setFont ( new Font ( "Avenir" , Font . BOLD , 15 ) ) ; startButton . addActionListener ( new ActionListener ( ) { @ Override public void actionPerformed ( ActionEvent e ) { setVisible ( false ) ; dispose ( ) ; SwingUtilities . invokeLater ( new Runnable ( ) { public void run ( ) { try { MainMenu . createAndShowGUI ( ) ; } catch ( IOException e ) { e . printStackTrace ( ) ; } } } ) ; } } ) ; mainPanel . setLayout ( new GridBagLayout ( ) ) ; GridBagConstraints c = new GridBagConstraints ( ) ; c . fill = GridBagConstraints . HORIZONTAL ; c . gridx = 2 ; c . gridy = 1 ; c . insets = new Insets ( 5 , 15 , 5 , 15 ) ; mainPanel . add ( mainblock , c ) ; c . gridx = 2 ; c . gridy = 2 ; c . insets = new Insets ( 0 , 200 , 0 , 200 ) ; mainPanel . add ( startButton , c ) ; display . add ( mainPanel ) ; display . setVisible ( true ) ; } private static void createAndShowGUI ( ) { } public static void main ( String [ ] args ) { } }

Fix:
mainblock = new JLabel ( "<html><div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-family:<seq2seq4repair_space>Avenir;<seq2seq4repair_space>font-weight:<seq2seq4repair_space>bold;<seq2seq4repair_space>font-size:<seq2seq4repair_space>52pt;\">Team<seq2seq4repair_space>G<//div><div<seq2seq4repair_space>div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-size:<seq2seq4repair_space>18pt;<seq2seq4repair_space>font-family:<seq2seq4repair_space>Avenir;\"><br>This<seq2seq4repair_space>software<seq2seq4repair_space>application<seq2seq4repair_space>is<seq2seq4repair_space>developed<seq2seq4repair_space>under<br><seq2seq4repair_space>the<seq2seq4repair_space>supervision<seq2seq4repair_space>of<seq2seq4repair_space>Professor<seq2seq4repair_space>Chris<seq2seq4repair_space>Johnson.<br>The<seq2seq4repair_space>program<seq2seq4repair_space>is<seq2seq4repair_space>based<seq2seq4repair_space>on<seq2seq4repair_space>the<seq2seq4repair_space>works<seq2seq4repair_space>of<seq2seq4repair_space>Arnaud<seq2seq4repair_space>Prouzeau.<br><seq2seq4repair_space><br><div<seq2seq4repair_space>style=\"text-align:<seq2seq4repair_space>center;<seq2seq4repair_space>font-size:<seq2seq4repair_space>12pt;\">Please<seq2seq4repair_space>be<seq2seq4repair_space>aware<seq2seq4repair_space>that<seq2seq4repair_space>not<seq2seq4repair_space>all<seq2seq4repair_space>satellite<seq2seq4repair_space>images<seq2seq4repair_space>are<seq2seq4repair_space>available<seq2seq4repair_space>for<seq2seq4repair_space>every<seq2seq4repair_space>location.<br>The<seq2seq4repair_space>trajectory<seq2seq4repair_space>is<seq2seq4repair_space>not<seq2seq4repair_space>based<seq2seq4repair_space>on<seq2seq4repair_space>complex<seq2seq4repair_space>formulae.<br>Please<seq2seq4repair_space>note<seq2seq4repair_space>that<seq2seq4repair_space>the<seq2seq4repair_space>helicopter<seq2seq4repair_space>size<seq2seq4repair_space>has<seq2seq4repair_space>been<seq2seq4repair_space>scaled<seq2seq4repair_space>for<seq2seq4repair_space>visual<seq2seq4repair_space>effect.<br>For<seq2seq4repair_space>help,<seq2seq4repair_space>hover<seq2seq4repair_space>over<seq2seq4repair_space>each<seq2seq4repair_space>component<seq2seq4repair_space>to<seq2seq4repair_space>view<seq2seq4repair_space>a<seq2seq4repair_space>tooltip." ) ;